HttpURLConnection 请求并接收参数

public void remoteService() throws Exception{
        //TODO  
        HashMap REQ_MSG_HDR=new HashMap();
        REQ_MSG_HDR.put("OP_CODE", "8888");             
        REQ_MSG_HDR.put("OP_WAY", "1");                 
        REQ_MSG_HDR.put("MSG_ID", "01");        
        REQ_MSG_HDR.put("OP_LANGUAGE", "1");         
        REQ_MSG_HDR.put("OP_CHANNEL", "001");             
        REQ_MSG_HDR.put("SESSION_ID", "");              
        String data =JSONObject.fromObject(REQ_MSG_HDR).toString();
        URL url=new URL("http://172.18.0.155:8080/rpc/test.do");
        //初始化链接connection
        HttpURLConnection conn=(HttpURLConnection)url.openConnection();
        //设置请求方式
        conn.setRequestMethod("POST");
        //开启输入输出
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setInstanceFollowRedirects(true);
        //设置请求头
        conn.setRequestProperty("Content-Type", "application/json");
        conn.connect();
        //将参数以流的形式传入request
        OutputStreamWriter  out = new OutputStreamWriter(conn.getOutputStream());
        out.write(data);
        out.flush();
        out.close();
        //获取请求响应结果
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        System.out.println("=============post================");
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        reader.close();
        conn.disconnect();
    }